To the surprisingly inventive uses for banana peels -- which include polishing silverware, leather shoes, and the leaves of house plants -- scientists have added purification of drinking water contaminated with potentially toxic metals. Their report, which concludes that minced banana peel performs better than an array of other purification materials, appears in ACS's journal Industrial & Engineering Chemistry Research.

The slippery yellow skins are better known as a comedic prop, but now research has demonstrated they have a capacity to absorb lead and copper from river water. Previously, other plant materials such as peanut shells and coconut fibers had been tried, but minced banana peels did the trick better.

Researchers also found minced banana peels could be used repeatedly to purify water contaminated by industrial plants and farms – up to eleven times – and still be effective. In their study paper titled “Banana Peel Applied to the Solid Phase Extraction of Copper and Lead from River Water: Preconcentration of Metal Ions with a Fruit Waste” they also noted the very low cost of banana peels and the fact there is no need to prepare them chemically for the water purification procedure.

Gustavo Castro and colleagues note that mining processes, runoff from farms, and industrial wastes can all put heavy metals, such as lead and copper, into waterways. Heavy metals can have adverse health and environmental effects. Current methods of removing heavy metals from water are expensive, and some substances used in the process are toxic themselves. Previous work has shown that some plant wastes, such as coconut fibers and peanut shells, can remove these potential toxins from water.

Using materials produced naturally is also helpful because they are less likely to result in extra contaminants being introduced into the polluted area. Some remediation projects use manmade chemicals to address the pollution and risk additional contamination. A very obvious example is the use of chemical dipersants in the Gulf of Mexico after the recent huge oil spill. Some say their use only added to the marine contamination, and there isn’t enough long-term data for gauging the overall impact of mixing that much oil and dispersant on the ecosystem health and for humans.